Improvement in balanced slide-valves



UNITED STATES PATENT OFFICE.

A. S. CAMERON, OF NEW YORK, N. Y.

Specification forming part of Letters Patent No. 48,901, dated July 25,1865.

To all whom it may concern Be it known that I, A. S. CAMERON, on thecorner Twenty-Second street and Second avenue, in the city, county, andState of New York, have invented a new and Improved Balance Slide-Valve;and I do hereby declare that the following is a full, clear, and exactdescription thereof, which will enable others skilled in the art to makeand use the same, reference beinghad to the accompanyingdrawings,forming part of this specication, in which- Figure 1 represents alongitudinal vertical section of this invention. Fig. 2 is a transversevertical section of the same.

Similar letters of reference indicate like parts.

This invention relates particularly to slidevalves which take steam frombelow; and its object is to produce on the back of the valve a certainpressure somewhat stronger than the pressure which acts on the underside of the same, so that the valve is held on its seat with sufcientpower to prevent its jumping or unl seating.

The invention consists in combining with the valve one or more rollersand a diaphragm, which is exposed to the action of the steam and causedbythe steam to bear on the rollers and to hold them down upon the hackof the valve. The area of said diaphragm is so regulated that thepressure of the steam acting on it overbalances the pressure of thesteam acting on the under side ot the valve, and the valve isconsequently held down on its seat with sufficient force to prevent itfrom jumping. In order to keep the rollers parallel on the back of thevalve, they are provided with cogs at both ends, and these cogs gear incorresponding racks secured to the back of the valve, near its edges.

A represents the steam-chest of an ordinary steam-cylinder, which takessteam through the channels a a,'and to whichpsteam is admitted throughthe channel b.

B is the slide-valve, and the steam-channel b communicates with theports a a through the cavitycin the under side of the valve. In valvesof this description the pressure of the steam has a tendency to throwthe valve o" from its seat, and it is therefore necessary to apply somedevice capable of holding the valve down without preventing it fromtraversing on its seat. I have effected this object by means of adiaphragm, C, which forms a partition in the valve-chest7 dividing thesame in two compartments, d e. The upper compartment communicates, by asuitable passage in the side of the valve-chest, with the steam-channelb, so that the upper surface of the diaphragm is exposed to the fullpressure of the live steam. Said diaphragm is made ofsheet metal orother suitable material, and it is strengthened by the platesfg, one ontop and one below. The lower plate, g, bears on rollers D D, which reston the back of the valve. These rollers are provided with cogs IL attheir ends, which gear in toothed racks 1'., secured to or formed intheback of the valve, near its edges, as clearly shown in Fig. 2 ot' thedrawings. When the steam-pipe is opened and stealn admitted to thechannel b the upward pressure of the valve is counteracted by thedownward pressure on the diaphragm, and the effective surface ot' thisdiaphragm is so regulated that the downward pressure of the sameoverbalances the upward pressure on the valve, and the latter is held onits seat with sufficient power to prevent leakage, and at the same timethe whole is so arranged that the valve moves on its seat with the leastpossible loss by friction. Any

increase ordecreasein the pressure ofthe steam has no effect on themotion ofthe valve; and, it' desired, the effective surface ot' thediaphragtn can be made adjustable by means of the slides j, so that thesame can be adjusted according to circumstances.

rIhe cogs at the ends ofthe rollers keep the same parallel, and thepressure exerted by the diaphragm on the rollers is transmitted to theback of the valve with the least possible loss by friction.

The .object ot' keeping the rollers parallel would be effected, however,by running connections from one to the other or by other equivalentmeans, and I do not wish to coniine myself to the means shown in thedrawings.

I claim as new and desire to secure by Letters Patentl. The combinationofthe diaphragm O, rollers D, and valve B, constructed and operatingsubstantially as and for the purpose set forth.

2. The arrangement of cogs or their equivalents at the ends of therollers and corresponding toothed rackson the back of the slide-valve,substantially as and for the purposes described.

A. S. CAMERON.

Witnesses:

WM. DEAN OVERELL, M. M. LIVINGSTON.

